Structural, compositional and annealing effects on magnetic properties in R1−xCox(R = Er, Tb, Sm) amorphous thin film alloys

Amorphous alloys of the rare earths and transition metals series possess unique magnetic properties which are highly dependent on the alloy compositions and the microstructure. The magnetic properties have been investigated in various sputtered R1−xCox amorphous thin film alloys presenting highly anisotropic magnetic systems. Samples have been annealed for different temperatures. The magnetic changes, at various composition and various temperatures, have been measured by vibrating sample magnetometer (VSM); the structural and compositional properties have been investigated utilizing Rutherford back scattering (RBS) and scanning electron microscopy (SEM) analysis. The most significant results are: (1) Curie temperatures Tc above room temperature and coercivity Hc are strongly dependent on the alloys composition; moreover, the shapes of hysteresis loops are affected and (2) field annealing (before temperature of crystallisation) makes the samples magnetically softer (reducing Hc) and reduce the internal stress induced during the deposition by inducing a well defined anisotropy.